Television deflection power recovery circuit



June 5, 1951 A. A. BARCO 2,555,829

' TELEVISION DEFLECTION POWER RECOVERY CIRCUIT Filed April 30, 1949 14SYNC 10 20 omzcr/m .s/a/v/rz awn/we INVENTOR AME/v 4 54/?00 PatentedJune 5, 1 951 TELEVISION DEFLECTION POWER RECOVERY CIRCUIT Allen A.Barco, Princeton, N. J assignor to Radio Corporation of America, acorporation of Delaware Application April 30, 1949, Serial No. 90,571

Claims. 1

The present invention relates to electrical damping systems of thereaction scanning power recovery type and more particularly toelectromagnetic cathode ray beam deflection circuits of the typeemployed in television systems wherein a portion of the damped reactiveenergy in the deflection system is fed back for utilization by thedeflection circuit to thereby improve the overall operating efficiencyof the system.

Generally speaking, in electrical circuits wherein some form of dampingaction is required, the overall efficiency of operation is considerablylowered because of the energy dissipated in the damping circuits, thisenergy not being gainfully utilized. In early television practice,cathode ray electromagnetic beam deflection systems sufiered substantiallosses in this respect, which in turn stimulated the development ofpower recovery deflection systems in which some of the storedelectromagnetic reactive energy, normally dissipated in the dampingsystem, is capacitively stored and employed to efiect a boost in the Bsupply voltage applied to the vacuum tube driving the deflection system.Such power recovery or power feedback systems have greatly improved theoperating efiiciencies obtainable in deflection systems as a whole.However, most prior art systems of this kind require the utilization ofa deflection coupling transformer in order to realize reactive dampingcurrents of proper magnitude to readily permit power feedback into the Bsupply circuit of the driving vacuum tube.

The use of a transformer in this connection, of

course, represents certain additional costs in circuit construction aswell as introducing inherent losses in the system due to leakagereactanceand magnetic hysteresis. The losses incurred through use of atransformer for coupling energy from the plate circuit of the deflectiondriving tube to the damped deflection yoke of course may be obviated bydirect inclusion of the yoke in the anode circuit of the vacuum tube.ever, until recently, a direct drive reaction scanning connection ofthis type has not been re-' covery action. The major problem with this:particular form of direct drive system, as well.

as other prior art arrangements, is that of obtaming sufiicientlinearity of sweep during that How reaction scanning operation inaddition to cor-.

recting for the non-linearity of sweep distribution due to flatness ofthe cathode ray tube.

. screen.

Furthermore, in television receiver applications, the direct drivearrangement for the de-' fiection yoke has in the past displayed anotherawkward feature, that being the difliculty of obtaining from thedeflection system an economical form of pulse step-up power supply fordevelopment of an accelerating potential for the associated cathode rayreproducing device. In a co-pending application by Simeon I. Tourshouand William E. Scull, Jr., Serial No. 56,562 filed October 26, 1948,entitled High Voltage Power Supply, this latter difficulty has beenovercome in part through the use of an autotransformer having itsprimary connected in series with the deflection yoke circuit. The highvoltage pulses appearing in the secondary winding are then rectified toproduce the appropriate high unidirectional beam accelerating potential.The inclusion of this autotransformer primary in the yoke circuit does,however, reduce to a considerable extent the operating voltage actuallysupplied to the anode of the output tube and consequently a somewhathigher B+ power supply potential is normally required to correct forthis voltage drop. This provision of such an increase in the initial Bpotential represents considerable additional cost in the de-- sign ofthe television receiver low voltage power supply.

The present invention aims to provide a high efliciency low costreaction scanning system of the direct drive B boost type whichovercomes some of the disadvantages hereinabove set forth.

It is therefore a purpose of the present invention to provide animproved form of reaction scanning power recovery damping system fordirect drive electromagnetic beam deflection systems which exhibits aneflicient B boost action with an attendant high degree of deflectionlinearity.

Another object of the present invention restsin the provision of a noveland simple B boost circuit for direct coupled electromagnetic cathoderay beam deflection .yokes in which energy from an associated reactionscanning damping circuit is recovered for B boost action and in whichsuch a B boost recovery action is compensated in the reaction scanningcycle to provide substantially linear deflection operation.

1 It isanother purpose of the present invention.

3 to provide an improved form of deflection circuit for televisionsystems wherein a portion of the cyclically damped reactive energy inthe yoke circuit is applied for effectively boosting the availablepolarizing potential of the driving vacuum tube.

Still another object of the present invention resides in the provisionof a novel form of power recovery system particularly applicable todirectly driven electromagnetic deflection coils in television systemswherein the deflection coils are included in the series with theanode-cathode circuit of the deflection system driving vacuum tube.

A still further object of the present invention is to provide certainimprovements in the waveform of the deflection signal developed by thepower recovery apparatus shown in my copending application, Serial No.62,844, filed December 1, 1948.

The present invention has numerous other objects and features ofadvantage, some of which, together with the foregoing will be set forthin the following description of specific apparatus embodying andutilizing the inventions novel method. It is therefore to be understoodthat the present invention is not limited in any way to the apparatusshown in the specific embodiments as other advantageous applications inaccord with the present invention, as set forth in the appended claims,will occur to those skilled in the art after having benefited from theteachings of the following description especially when considered inconnection with the accompanying drawings in which:

Figure 1 shows by circuit diagram one form of the present invention asapplied to a typical direct driven television deflection system;

Figure 2 shows by circuit diagram another form of the present inventionas applied to a direct driven deflection system similar to that shown inFigure 1.

Referring now to Figure 1, there is shown a portion of a typicaltelevision deflection system. Here synchronizing pulses are applied atterminal ll) to synchronize the operation of deflection signal generatorl2, which in turn produces a conventional deflection sawtooth waveformillustrated at M. The signal I4 is then applied to grid I6 of a cathodefollower vacuum tube l8. The anode 20 of vacuum tube l8 accordingly isconnected through a dropping resistor 22 to a source 24 of anodepolarizing potential. The condenser 26 establishes the anode 20 atsubstantially A. C. ground potential. A suitable cathode followerresistor 28 is connected in the cathode to ground circuit of the vacuumtube 18 so as to provide a low impedance driving source for the grid 30of output vacuum tube 32. A suitable negative operating bias is achievedfor the grid 30 by inclusion of resistor 34 in the oath-- ode groundcircuit of vacuum tube 32. Rheostat 36, connected from a source ofpositive potential 38 connected to the top of resistor 34, allows thevoltage drop across resistor 34 to be sufficiently in excess of the D.C. voltage drop across cathode follower resistor 28 to establish propernegative grid biasing of the tube 32. A cathode by-pass condenser, suchas 40, may be provided to reduce signal degeneration in the cathodecircuit of the output tube. Screen grid 42 is conveniently supplied Witha positive polarizing potential indicated as S. G.

The anode 50 of the output vacuum tube 32 is then connected to a sourceof positive polarizing 4 potential having a terminal at 52 through theseries circuit comprising the primary winding 54 of autotransformer 56,the first section 58 of the deflection coil XX, a storage capacitor 66,and the second section 32 of the deflection coil XX. In accordance withmy co-pending application, Serial No. 62,844, supra, damper diodes suchas 64 and 55 are respectively connected through the storage capacitor asfor damping the respective sections of the deflection coil 58 and 62.

According to the present invention, a lowpass filter circuit isconnected between each of the damping diodes 64 and 66 and the storagecapacitor 60. In the arrangement shown in Figure 1, the filter circuitshown associated with diode 64 comprises the inductance 68 and thecapacitor Hi while the inductance l2 and associated capacitor M form thelow-pass filter for the diode 68. It is noted in the case of Figure 1that the inductive elements 68 and 72 provide a direct currentconductive pathfrom the respective diodes to opposite terminals of thecapacitor 60.

As is shown, a novel'form of high voltage power recovery supply for theaccelerating anode 16 of the kinescope I8 is provided through the use ofthe autotransformer 56. This form of high voltage power supply for usein connection with deflection systems having deflection yoke directlyconnected in the anode-cathode circuit of the driven vacuum tube it isdisclosed in the abovecited co-pending application by Simeon I. Tourshouet al., Serial No. 56,562. As more fully described in the Tourshou etal. specification, the output tube deflection current for the yokewinding XX passes through the primary winding 54 of the autotransformer55 and thereby induces in the autotransformer secondary 51 highv voltagepositive pulses corresponding in time to the kickback pulses 5!occurring at the plate 50 of the output tube 32. These high voltagepulses are then rectified by the diode to develop a high unidirectionalpotential across the storage capacitor 82. The voltage appearingthereacross is further filtered through the resistor 84 acting incombination with stray circuit capacitance and applied to acceleratingterminal 16 of the cathode ray tube E8. An auxiliary winding 86 of thetransformer 56 may be arranged to supply heater power for the filament58 of the high voltage rectifier 80.

As described in my co-pending application, Serial No. 62,844 filedDecember 1, 1948, the damping diodes 64 and 66 operate in accordancewith basic reaction scanning deflection system operation in relationshipto the individual sections of the deflection windings 58 and 62.Accordingly, the first part of the deflection cycle, which will be hereconsidered as resulting from the reaction scanning effect of theindividual diode damping, is provided by energy stored in the respectiveinductances 58 and 62 at the end of the retrace phase of the deflectioncycle. It is well known to those skilled in the television art thatimmediately following the retrace or return phase of the deflectioncycle, at which time there is zero current through the vacuum tube 32,the diodes 64 and 65 will become conductive to establish a reversedcurrent flow through the respective winding sections, the current energyof which represents the stored magnetic energy in these coil sections.For instance, in the case of the diode 64, immediately followingretrace, the diode 54 will become conductive to pass a damping currentId in the direction of the arrow 90. This passage of current in thedirection indicated in effect adds energy to the capacitor 60 therebymaking the terminal 92 thereof more positive than its correspondingterminals 94. In similar fashion the damping current of diode 66connected to damp the second portion 62 of the yoke winding XX is in thedirection of the arrow 96, and can be seen to also add energy to thecapacitor 60 and thereby cause the terminal 92 to charge positively withrespect to the terminal 94. It is clear that the damping currentsthrough the respective diodes 64 and 66 occur simultaneously so that asfar as the yoke XX is concerned a proper overall damping arrangement hasbeen provided, the respective damping currents through the diode inpractice being substantially equal.

Investigation of the circuit arrangement shows that the capacitor 60 isin fact placed in series between the positive B supply terminal at 52and the anode 50 of the vacuum tube 32 so that any voltage developedacross capacitor 60 is additively combined with the positive B supply.Thus, damped reactive energy is stored by capacitor 60 during thereaction scanning cycle and made ready for use by the tube 32 during theensuing driven phase of the deflection cycle.

- It will be appreciated that if the storage capacitor 60 is madesufliciently large that its terminal voltage during the conductionperiod of the driver tube 32 will remain substantially constant allowingthe production of a substantially linear sawtooth of current through thedeflection coil XX. As is well known to those skilled in the art, it is,however, not always desirable to produce a perfect sawtooth of currentin order to achieve linear scanning distribution of the beam on the faceof the kinescope. Such factors as the flatness of the cathode ray tubescreen surface and the non-linear fiuX distribution of averagedeflection yoke coils make it often desirable to generate through thedeflection coil itself a sawtooth of current having considerabledeliberate distortion of a variety tending to compensate for thesefactors.

According to the embodiment of the present invention, as illustrated inFigure 1, in order to achieve proper shaping of the sawtooth currentthrough the yoke, there is placed in the damping circuit of each diode alinearity control inductance, such as 68 and 12. Correspondingcapacitors, such as and 14, are then connected from the diode sides ofthe linearity control inductances to the opposite terminal of thestorage capacitor 60.

With such an arrangement, the voltage variation of substantiallysawtooth waveform appearing across the storage capacitor 60 duringconduction of vacuum tube 32, will be shaped-by the low-pass filtersformed by the linearity control inductances 68 and 72 with theirrespective shunt capacitances 10 and 14. The resulting voltage will besomewhat parabolic in form and will in effect be placed in series withthe anode-cathode circuit of the damper diodes. This parabolicallyvarying voltage in the damping circuit will then act as a variable biasfor the diodes 64 and 66 and act to control their degree of conductionduring circuit operation. It is found that this control bias on thedamper diodes so alters the resulting current flow through the yokewindings 58 and 62 to produce a linear deflection distribution of thebeam on the cathode ray'tube face and hence produce a high degree ofoverall deflection circuit linearity. The. inductances 68,

'ing the shaping network, may be made variable so that the linearity andsize of the resulting deflection signal may be easily controlled.Furthermore, a variable resistor, such as 59 (shown in dotted lines),may be placed in shunt with the capacitor 64 in order to provide afurther control over the waveform and size of the resulting deflectioncurrent. This resistance 59, althrough not necessarily employed, mayassume values of from 5,000 to 10,000 ohms.

Another form of the present invention is shown in Figure 2, here thedeflection signal output tube 32 is operated as in Figure 1 with asimilar form of high voltage autotransformer 56 connected in its'platecircuit to provide accelerating potential for the kinescope 18. As inFigure 1, the deflection yoke winding XX is split into two sections 58and 62 and connected by the B boost storage capacitor 60. Damping diodes64 and 66 are again connected in shunt with the deflection coil sections58 and 62 respectively and have in their respective damping circuits,the linearity control inductances 68 and 12. Here, however, theindividual low-pass filter condensers 10 and 14 (in Figure 1) areomitted and replaced by a single capacitor I00 connected between the twolinearity control inductances 68 and 12 at their damping diodeterminations. This arrangement also provides shaping of the sawtooth ofcurrent normally appearing across the capacitor 60 and serially imposesan A. C. bias of parabolic waveform in series with each of the dampingdiodes thereby correcting the current sawtooth through the deflectionyoke to achieve proper and linear distribution of the beam deflection onthe kinescope screen. In practice, the arrangement in Figure 2 is foundto yield results substantially equivalent to the arrangement of Figure 1with the additional advantage of decreased circuit complexity and cost.Again, the individual linearity inductances 68 and 12 may be madevariable as well as the capacitor to act as a linearity and/or sizecontrol in the circuit. Moreover, a variable resistor such as 59 inFigure 1 may be placed in shunt with the capacitor 60 if further controlover the size and linearity of the deflection action is desired.

In the practice of the present invention, it may be found thatunavoidable stray circuit capacitances acting in combination with thelinearity control inductances 68 and 12, as well as the elfectiveinductive reactance of the primary 54 of the autotransformer 55 and thereactance of the deflection yoke itself will be responsible for theoccurrence of spurious transients in the generated deflection signalcurrent. It has been found that such transients may be notably reducedby employing linearity inductances having a sufliciently low Q. For agiven linearity inductance Q, however, it is evident that the transientscould also be reduced by applying damping resistors of a suitable value,such as I02 and I04 (shown in dotted lines in Figure 2) in shunt withthe linearity control inductances. Furthermore, although a particulartype of low-pass filter has been shown in Figures 1 and 2, it ismanifest that more complex and different types of low-pass filters couldbe employed without departing from the spirit and scope of the presentinvention.

From the foregoing it can be seen that the applicant has provided animproved form of direct drive deflection circuit which provides reactionscanning andB boost power recovery with,

ploys a winding of a deflection yoke connected in V series with theanode-cathode circuit of an electronic output amplifier, a capacitorconnected in series with the deflection yoke winding in the outputamplifier anode-cathode circuit, a lowpass filter connected in shuntwith a portion of the amplifier anode-cathode circuit which in- I eludessaid capacitor a portion of said low-pass filter being conductive todirect current, and an electrical damperconnected in shunt with aportion of said output amplifier anode-cathode circuit through at leastthe direct current conducting portion of said low-pass filter.

2. In an electromagnetic cathode ray deflection system of the directdrive type which employs a deflection yoke coil connected in series withthe anode-cathode circuit of an electronic output amplifier, a capacitorconnected in series with the deflection yoke coil in the outputamplifier anode-cathode circuit, a low-pass filter connected in shuntwith a portion of the amplifier anode-cathode circuit which includessaid capacitor, a portion of said low-pass filter being conductive todirect current, and an electrical damper connected in shunt through thedirect current conducting portion of said low-pass filter with a portionof said anode-cathode circuit which embraces the series connection ofsaid capacitor and deflection yoke.

3. In a cathode ray beam deflection and accelerating potentialgenerating system of the type employing an electron discharge tubehaving directly connected in its anode-cathode circuit the seriescombination of a pulse step-up transformer primary winding and a cathoderay beam deflection yoke winding, such that undesirably excessiveunidirectional voltage drop is produced across the pulse step-uptransformer primary winding thereby tending to evasively reduce theactive anode-cathode biasing potential of the electron discharge tube, apower recovery unidirectional potential boosting arrangement comprisingin combination: a storage capacitor connected in series with theelectron discharge tube anode-cathode circuit between the pulse step-uptransformer primary winding and said deflection yoke winding, a low-passfilter circuit connected in shunt with said storage capacitor, saidlow-pass filter having a portion thereof conductive to direct current, aunilaterally conductive damping device connected in shunt through thedirect current conductive portion of said low-pass filter with theseries connection of the storage capacitor and at least a portion ofsaid deflection yoke such that the voltage developed across said storagecapacitor tends to compensate for the undesirable excessive voltage dropacross said pulse step-up transformer primary winding.

4. In a cathode ray beam deflection and accelerating potentialgenerating system of the type employing an electron discharge tubehaving directly connected in its anode-cathode circuit the seriescombination of a pulse step-up transformer primary winding and a cathoderay beam deflection yoke winding such that an undesirably excessiveunidirectional voltage drop is produ'ced across the pulse 'step-uptransformerpri mar-y winding thereby tending to reduce the averageanode-cathode biasing potential of the electron discharge tube, a powerrecovery unidirectional potential boosting arrangement comprising incombination: a storage capacitor serially connecting the primary of saidpulse step-up transformer with one terminal of said deflection yokewinding, an inductance and a capacitance connected in series with oneanother to form a wave-shaping network, connections placing saidWave-shaping network in shunt "with said storage capacitona unilaterallyconductive damping device having an anode and a cathode, a connectionfrom said damping device cathode th'rough'said inductance "to thestep-up transformer primary winding side of said storage capacitor, anda connection from said damping device anode to another terminal on saiddeflection yoke.

5. Apparatus according to claim 4 wherein said inductance connected inseries with said capacie tance to form said wave-shaping network isrestricted 'inQ in accordance with undesirable'cir cuit transients so asto minimize the appearance of these transients in the waveform ofcurrent through said deflection yoke winding.

6. In a cathode ray beam deflection and accelerating potentialgenerating system of the type employing an electron discharge tubehaving directly connected in its anode-cathode circuit the seriescombination of a pulse step-up transformer primary winding and a cathoderay beam de'fi'e'ction yoke winding, such that an undesirably excessiveunidirectional voltage drop is produced across the pulse step-uptransformer primary winding thereby tending to reduce the activeanode-cathode biasing potential of the electron discharge tube, a powerrecovery unidirectional potential boosting arrangement comprising incombination: a storage capacitor connected to one terminal of saiddeflection yoke winding, an inductance and a capacitance connected inseries to form a wave-shaping network, connections placing saidwave-shaping network in shunt with said storage capacitor, aunilaterally conductive damping device having an anode and a cathode, aconnection from said damping device anode through said inductance to oneside of said storage capacitor, and a connection from said dampingdevice cathode to another terminal on said deflection yoke.

'7. In an electromagnetic cathode ray deflection system of the directdrive type which em ploys a deflection coil directly connected in theanode-cathode circuit of an output amplifier, the combination of, afirst capacitor connected in series with said deflection coil in theoutput amplifier anode-cathode circuit, an inductance and secondcapacitor connected in series with one another to form a combination,said serially; connected inductance and capacitor combination beingplaced in shunt with a portion of the am-- plifier anode-cathode circuitincluding said first capacitor, and an electrical damper connected inshunt with a portion of said output amplifier anode-cathode circuitthrough at least a portion of said inductance.

8. In an electromagnetic cathode ray deflec-I tion system of the directdrive type which employs a deflection coil directly connected in theanode-cathode circuit of an output amplifier, the combination of, afirst capacitor connected in series with said deflection coil in theoutput amplifier anode cathode circuit, an-ind'uctance-and secondcapacitor connected in series with one another to 'form a combination,said serially connected inductance and capacitor combination beingplaced in shunt with a portion of the amplifier anode-cathode circuitincluding said first capacitor, and an electrical damper connected inshunt with a portion of said output amplifier anode-cathode circuitincluding said first capacitor and deflection yoke through at least aportion of said inductance.

9. man electromagnetic cathode ray defiection system of the direct drivetype which employs a deflection coil directly connected in theanode-cathode circuit of an output amplifier, the deflection Y coilcomprising a first and second winding section, each having an inner andouter extremity,the combination of: a storage capacitor connected inseries with the anode-cathode circuit of said amplifierbetween the innerextremities of the first and second deflection yoke winding sections, alow-pass filter having a first and second input terminals andcorresponding first and second output terminals, a connection betweenthe first deflection winding inner extremity and said filter first inputterminal, connections between said second winding inner extremity andsaid second filter input terminal, a first unilaterally conductivedamping device connected between the outer extremity of said firstdeflection winding section and said filter second output terminal, asecond unilaterally conductive damping device connected between theouter extremity of said second deflection yoke winding section and saidfilter first output terminal.

10. In an electromagnetic cathode ray deflection system of the directdrive type which employs a deflection coil directly connected in theanode-cathode circuit of an output amplifier, the deflection coilcomprising a first and second winding section, each having an inner andouter extremity, the combination of: a first capacitor connected inseries with the anode-cathode circuit of the output amplifier betweenthe inner extremities of the deflection yoke first and second windingsections, a first network comprising the series connection of aninductance and capacitance, said first network being placed in shuntwith said first capacitor, a first and second unilaterally conductivedamping devices, each having an anode and a cathode, a connectionbetween the outer extremity of the first yoke winding section and thefirst clamping device cathode, a connection between the outer extremityof the second yoke winding section and the second damping device anode,an inductance connected between the inner extremity of the first yokewinding section and the cathode of the second damping device, aninductance connected between the inner extremity of the second yokewinding section and the anode of the first damping device, a capacitanceconnected between the inner extremity of the first yoke winding sectionand the anode of the first damping device, and a capacitance connectedbetween the inner extremity of the second yoke winding section and thecathode of the second damping device.

11. Apparatus according to claim 10 wherein said inductance connectedbetween the inner extremity of the first yoke winding section and thecathode of the second damping device and said inductance connectedbetween the inner extremity of the second yoke winding section and theanode of the first damping device are each restricted in Q such tominimize spurious deflection lfl capacitor connected in series with theanodecathode circuit of the output amplifier between the innerextremities of the deflection yoke first and second winding sections, afirst network comprising the series connection of an inductance andcapacitance, said first network being placed in shunt with said firstcapacitor, a first and second unilaterally conductive damping devices,each having an anode and a cathode, a connection between the outerextremity of the first yoke winding section and the first damping devicecathode, a connection between the outer extremity of the second yokewinding section and the second damping device anode, an inductanceconnected between the inner extremity of the first yoke winding sectionand the cathode of the second damping device, an inductance connectedbetween the inner extremity of the second yoke winding section and theanode of the first damping device, a capacitance connected between theinner extremity of the first yoke winding section and the anode of thefirst clamping device, and a capacitor connected between the anode ofthe first damping device and the cathode of the second damping device.

13. Inan electromagnetic cathode ray beam deflection system employing adeflection coil comprising at least a first and second separate windingsections, each section having a first and second utilization terminals,a power recovery damping arrangement comprising in combination: a vacuumtube having at least an anode and a cathode, said vacuum tube beingconnected for excitation from a source of deflection signal, a source ofpolarizing potential for said vacuum tube anode-cathode circuit, astorage capacitor connected from the first terminal of the firstdeflection coil winding section to the first terminal of the seconddeflection coil winding section, means coupling deflection energy fromsaid vacuum tube anode-cathode circuit to said deflection coil windingsections, a first and second unilaterally conductive damping deviceseach having an anode and a cathode, an inductance connected between thefirst damping device anode and the first terminal of the second coilwinding section, an inductance connected between the cathode of thesecond clamping device and the first terminal of the first coil windingsection, a connection between the first damping device cathode and theanode terminal of the first coil winding section, a connection betweenthe second damping device anode and the second terminal of the secondcoil winding section; a capacitor connected between the anode of thefirst damping device and. the cathode of the second damping device, andconnections applying the terminal voltage developed across said storagecapacitor as the result of the combined separate damping sections ofsaid first and second damping devices in series with said source ofpolarizing potential and said vacuum tube anode-cathode circuit.

14. In an electromagnetic cathode ray deflection system of the directdrive type which employs a deflection coil directly connected in theanode-cathode circuit of an output amplifier in cathode circuit; aninductancecandi second capacitorr' connected: in serieswitlr oneanother; said serially connected inductance and? capacitorbeingzplacedin shunt-with a portion of theamplifier anodes-cathodecircuitincluding saidfirst capacitor; atidamping element having an anodeanda cathode, a connection from: said'anode to the amplifier cathodeside of said deflection yoke, and aiconnectiorrfromisaid"damping-elementcathode tozsaidiinductance;

15'; In: an 'electromagneticcathode ray beam deflection'systememploying'a deflection coil compri'sing at least a'first'and'secondseparate windingsections; each-section having a first and secondutilization terminals; axpower recovery damping. arrangement; comprisingin. combination: a vacuum: tube' having" at" least an anode and acathode, saiidvacuumv tube being" connected for excitationfrom-a sourceof deflection signal, a source-of polarizing potential for said vacuumtube' anode-cathode circuit; a storage capacitor connected from thefirst'terminal of the first dean anode: and a cathode, an inductanceconnected between the firstdampingdevice anode and the first terminalof'th'e second coil winding section,

a second capacitor. connected between the-first terminal of the secondcoil winding; sectionvand; the cathode of the second dampingdevice, andconnections applying the terminal voltage-developed across said storagecapacitor asvthe result'of the combined separate dampingqsections of'said; first and second clamping devices'in series withsaid source ofpolarizing potential. and saidvacuum tube anode-cathode circuit.

ALLEN A. BARCO.

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